Open topped compartments, such as truck trailers, dump trucks, storage bins and the like used for hauling or storing particulate material such as grain, ash, lime or the like are subject to having the material fall or blow out onto the roadway. Exposure to rain, excessive sunlight, etc., is often damaging to materials being hauled or stored. With materials such as gravel, aggregate or similar materials, having portions of a load fall onto a roadway is undesirable both from the point of view of littering and the danger of the material striking a following vehicle, possibly breaking a windshield or causing an accident. Where heated materials, such as asphalt, are being stored or carried, retention of heat within the container is very desirable.
Many localities now have laws requiring that all open topped vehicle compartments be covered when containing loose or lightweight material. Often, the loads are simply covered with a tarpaulin that is tied to the edges of the open top at intervals around the opening. While sometimes effective, such tarpaulins are difficult for one person to put into place, especially in windy conditions. Often, it is necessary for the operator to climb on the vehicle or bin sides or across the load to secure the tarpaulin, at considerable personal danger. Installation is time consuming and must be carefully done to prevent an edge of the cover from loosening, allowing spillage of part of the load.
Attempts have been made to provide more convenient covers that are rolled or folded at one end of the compartment and can be unrolled or unfolded to cover the load. These arrangements are generally difficult to deploy and do not adequately secure the sides of the cover to the container sides.
Where a container is filled or overfilled with a granular material, such as dirt or gravel, to the point where the material extends above the container walls, moving a cover over the container surface, typically along and generally parallel with the container upper wall edges, is difficult. The cover edge moving along the container edges tends to dig into the material. Forcing the cover edge through the material is difficult, often impossible for a single operator. In addition, some of the material may be spilled or end up on top of the cover, defeating the purpose of the cover, since spilled or loose material on the cover will fall to the roadway, endangering other vehicles and violating laws and regulations governing covered loads.
Thus, there is a continuing need for improvements in deployable covers for open topped compartments and systems for installing them that will fully and uniformly restrain material loaded in the compartment along both the ends and sides of the compartment, can be easily moved into and out of the covering position by one person standing on the ground, will fully cover material that extends above the compartment sides and will avoid forcing heaped material over the compartment side or onto the cover upper surface from which it can fall to the roadway.